A multilayer silver halide color photographic material has on a support a multilayer structure of light-sensitive layers, composed of three kinds of silver halide emulsion layers selectively sensitized to have sensitivities for blue light, green light, and red light, respectively.
For forming color photographic images, the color photographic material containing yellow, magenta, and cyan photographic couplers in the light-sensitive layers, respectively, is imagewise exposed and processed by a color developer containing an aromatic primary amine color developing agent. Colored dyes are formed by the coupling reaction of these couplers and the oxidized product of an aromatic primary amine, and it is preferred to use couplers showing a coupling rate as high as possible and a good coloring property for giving a high color density in a limited development time. Furthermore, the colored dyes are required to be clear cyan, magenta, and yellow dyes having low side absorption and providing color photographic images with good color reproducibility.
The color photographic images formed are required to have a good storage stability under various conditions, including, for example, a dark storage condition under influences of humidity and heat and a light irradiation condition by sun light or room light. The occurrence of discoloring and fading of color images as well as yellowing of background portions (in particular, color photographic papers) is a very serious problem.
For meeting these requirements for color photographic materials, the role of couplers as the color image-forming agents is large and improvement of coupler structures has been made. As one such improvement, phenol derivatives or naphthol derivatives are mainly used as cyan couplers but since the color images formed therefrom have unnecessary absorption in not only the red region but also blue regions and green regions, it cannot be said that they have satisfactory performances.
The imidazole cyan couplers described in British Patent 1,545,507 and European Patent 249,453A are excellent in light absorption characteristics of the color images formed, and are preferred for color reproduction.
However, when the imidazole cyan couplers are used for color photographic materials, the image storage stability of the color images formed after processing is inferior and, in particular, the color images are greatly faded by heat and humidity to give serious problems in practical use.
Since dyes derived from the imidazole couplers easily change to leuco dyes, recoloring of a cyan dye image portion in a bleaching or blix solution having a high desilvering property and a comparatively low pH is extremely deteriorated when the solution becomes to be fatigued. Such a defect has been a serious problem for attaining a quick and simple processing.